make-like file dependencies (aka is just a .PHONY replacement?)

[patmaddox]

It's been really easy to get going with just.

One thing I'm curious about: does it support make-like file dependencies, so it won't run a command if the file is up-to-date?

I think it doesn't, but I want to double check.

In that case, I think I can conclude two things:

1. just is essentially a cross-platform non-make-variant-specific replacement for .PHONY tasks (yes I've seen the idiosyncrasies FAQ)
2. If I want to generate files, I should still use make.

In other words, it gets me a "best tool for the job." Use make for generating files, and just for defining commands that I would otherwise shoehorn into .PHONY tasks. Does that sound right?

[casey]

You're correct, just does not support make-like file dependencies. Although I've thought of a syntax for adding it that I don't mind. Recipes with a name that's a string, instead of an identifier, would be file dependencies:

"a.out": "main.c"
  cc main.c

There's a lot more to figure out and implement, so it'll be a while before it's ready. In particular, Make has a lot of gotchas, so I want to make sure I avoid those.

In other words, it gets me a "best tool for the job." Use make for generating files, and just for defining commands that I would otherwise shoehorn into .PHONY tasks. Does that sound right?

Yup, that's correct. And you could also look at something like ninja as an alternative to make.

[patmaddox]

Cool, thanks, that makes sense.

you could also look at something like ninja as an alternative to make

Interesting, I hadn't come across this before. I've read through the manual a couple times, and some of the associated projects, still trying to wrap my head around it.

It seems like it's useful in things like C++ where you just have a compiler, but nothing to traverse all the source files. Whereas Rust has cargo, and in Elixir we have mix, so there's probably no point to using ninja there. Then again, that's back to my original point - that just is a good wrapper for mix and make (or ninja), or any build system.

The thing I may have to careful of is mixing these things up... because I can see how it would be useful for just to call the build systems - but also for build systems to call just (e.g. there's probably a useful just command to generate the ninja.build file). So there may be some aspect of layering here - a build.justfile with commands intended to be called from the build system, and a justfile that provides the top-level commands, which may include calling into the build system.

[danielb2]

I've been wondering about this too, so thanks for bringing it up pat and thanks for responding casey. I really make use of the dependencies for building stuff, but I think just is awesome. So I've kept using Makfiles for most things, and justfiles for the things that are just jobs.